mirror of https://github.com/joan2937/pigpio
73 lines
2.6 KiB
Markdown
73 lines
2.6 KiB
Markdown
# pigpio
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pigpio is a C library for the Raspberry which allows control of the
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General Purpose Input Outputs (GPIO).
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## Features
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* Sampling and time-stamping of GPIO 0-31 between 100,000 and 1,000,000 times per second
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* Provision of PWM on any number of the user GPIO simultaneously
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* Provision of servo pulses on any number of the user GPIO simultaneously
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* Callbacks when any of GPIO 0-31 change state (callbacks receive the time of the event
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accurate to a few microseconds)
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* Notifications via pipe when any of GPIO 0-31 change state
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* Callbacks at timed intervals
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* Reading/writing all of the GPIO in a bank (0-31, 32-53) as a single operation
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* Individually setting GPIO modes, reading and writing
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* Socket and pipe interfaces for the bulk of the functionality in addition to the
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underlying C library calls
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* Construction of arbitrary waveforms to give precise timing of output GPIO
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level changes (accurate to a few microseconds)
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* Software serial links, I2C, and SPI using any user GPIO
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* Rudimentary permission control through the socket and pipe interfaces so users
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can be prevented from "updating" inappropriate GPIO
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* Creating and running scripts on the pigpio daemon
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## Interfaces
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The library provides a number of control interfaces
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* the C function interface,
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* the /dev/pigpio pipe interface,
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* the socket interface (used by the pigs utility and the Python module).
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## Utilities
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A number of utility programs are provided:
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* the pigpiod daemon,
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* the Python module,
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* the piscope digital waveform viewer,
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* the pigs command line utility,
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* the pig2vcd utility which converts notifications into the value change dump (VCD)
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format (useful for viewing digital waveforms with GTKWave).
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## Example programs
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See http://abyz.co.uk/rpi/pigpio/examples.html.
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## GPIO
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ALL GPIO are identified by their Broadcom number. See http://elinux.org.
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There are 54 GPIO in total, arranged in two banks.
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Bank 1 contains GPIO 0-31. Bank 2 contains GPIO 32-54.
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A user should only manipulate GPIO in bank 1.
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There are at least three types of board:
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* Type 1
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* 26 pin header (P1)
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* Hardware revision numbers of 2 and 3
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* User GPIO 0-1, 4, 7-11, 14-15, 17-18, 21-25
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* Type 2
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* 26 pin header (P1) and an additional 8 pin header (P5)
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* Hardware revision numbers of 4, 5, 6, and 15
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* User GPIO 2-4, 7-11, 14-15, 17-18, 22-25, 27-31
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* Type 3
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* 40 pin expansion header (J8)
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* Hardware revision numbers of 16 or greater
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* User GPIO 2-27 (0 and 1 are reserved)
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It is safe to read all the GPIO. If you try to write a system GPIO or change
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its mode you can crash the Pi or corrupt the data on the SD card.
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